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...exible and wellspecified, so Tor can serve as a test-bed for future research. Many of the open problems in low-latency anonymity networks, such as generating dummy traffic or preventing Sybil attacks =-=[22], ma-=-y be solvable independently from the issues solved by Tor. Hopefully future systems will not need to reinvent Tor’s design. Simple design: The protocol’s design and security parameters must be wel...

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... i doesn't know anybody, or doesn't trust anybody, he will choose to trust the pre-trusted peers. Malicious Collectives. In peer-to-peer networks, there is potential for malicious collectives to form =-=[8]-=-. A malicious collective is a group of malicious peers who know each other, who give each other high local trust values and give all other peers low local trust values in an attempt to subvert the sys...

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...em. For example, a file sharing user might want to locate and retrieve a close-by replica of a file, while avoiding server or network failures. Security is also an important concern. The Sybil attack =-=[35]-=- is an attack where a user obtains a large number of identities to mount collusion attacks. Tapestry addresses this by using a trusted public-key infrastructure (PKI) for nodeID assignment. To limit d...

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... when attackers cannot choose nodeIds, they may still be able to mount all the attacks above (and more) if they can obtain a large number of legitimate nodeIds easily. This is known as a Sybil attack =-=[10]-=-. Previous approaches to nodeId assignment have either assumed nodeIds are chosen randomly by the new node [5] or compute nodeIds by hashing the IP address of the node [20]. Neither approach is secure...

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...tablish a pairwise key with any other nodes that have also erased KI (but a newly added node can still establish a pairwise key with it anyway). This helps prevent node clone attacks or sybil attacks =-=[8]-=-. In a clone attack, an attacker loads its own nodes with the keys of a compromised node, then deploys these cloned nodes in different locations of the sensor network. These cloned nodes then try to e...

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...uns multiple instances of Tarzan on different IP addresses. There are no known techniques to prevent this type of attack in a large-scale distributed system without some trusted centralized authority =-=[8, 9]-=-. 34However, Tarzan provides practical measures to lessen the impact of such attacks. First, nodes distribute their keys indirectly through a gossiping protocol. Second, tunnel initiators choose mimi...

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...ese messages are not susceptible to traffic analysis or denial-ofservice attacks by machines located outside of the administrative domain. Indeed, SkipNet even provides resiliency to the Sybil attack =-=[9]-=-: creating an unbounded number of nodes outside microsoft.com will not allow the attacker to see any traffic internal to microsoft.com. An attacker might attempt to target a particular domain (for exa...

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... the system are honest. For example, virtually all protocols for tolerating Byzantine failures assume that at least 2/3 of the nodes are honest. This makes these protocols vulnerable to sybil attacks =-=[9]-=-, in which a malicious user takes on multiple identities and pretends Permission to make digital or hard copies of all or part of this work for personal or classroom use is granted without fee provide...